Theclient->tags->getTags()function should return a collection however in the request it is failing and throwing an InvalidRequestError.
This error is only thrown if I were to execute iterator_to_array.
Example to replicate:
$client = Client::accessToken($api_token);
$existingAsanaTags = iterator_to_array($client->tags->getTags(), true);
print_r($existingAsanaTags);
Not sure what the Asana API is messing up in the URI as it appears to be calling a 'GET' to /tags and I am also using iterator_to_array($client->tasks->getTasksForProject($project_id), true); with no issues.